When you have a shingle home re-roofed, the first step is usually for the roofers to strip off the old shingles. Sometimes, homeowners wonder if this is necessary. It might seem like leaving those previous shingles in place would be easier and would even give your home an extra layer of protection. You may be particularly drawn to this line of thinking if you are seeing the mess that all those old shingles are creating as they're stripped off. But as good of an idea as it may seem on its face, leaving old shingles under the new ones is not typically a good idea. Here's why roofers remove them by default.
Old shingles are usually mossy and moldy.
Most roofs, by the time they are ready to be replaced, have some degree of mold or moss growth on or in them. If you put a new layer of shingles over these moldy ones, that will just trap moisture in the old shingles, shade them, and encourage the mold to keep growing more aggressively. The mold may soon start growing on the new shingles, too. The same is true of moss and algae, which also tend to grow on older roofs. Stripping off the old roof gives your new roof the best chance at a mold-free and moss-free existence.
Your roof underlayment may not be in great shape.
The underlayment is a layer of felt or waterproof plastic material that is under the shingles. This is an important layer of your roof as it offers a secondary level of protection when water gets past the shingles. Sadly, it can become damaged over time due to normal wear and tear. But your roofers need to strip the old shingles off to access it. If they just re-roof over the old shingles, you'll be left with the old underlayment, too, and it may not offer the protection it should.
Your shingle warranty may be void if the old shingles are not stripped away.
Shingle companies do require that their products are installed in certain ways in order for their warranties to be upheld. If the roofer violates these installation requirements, you won't have a warranty on your shingles. Usually, warranties require that the shingles are the only layer on the home, which is a big reason why roofers strip off old shingles first.
If you see your roofer stripping shingles off your roof, rest assured that this step is worth the work it takes. For more information, contact a roofing service in your area such as 503 Roofing and Construction, LLC.